Ecology, Evolution and Organismal Biology Ecology, Evolution and Organismal Biology Publications 2017 A New Species of Cotton from Wake Atoll,Gossypium stephensii(Malvaceae) Jonathan F. Wendel Iowa State University, [email protected] Joseph P. Gallagher Iowa State University Corrinne E. Grover Iowa State University, [email protected] Kristen Rex Colorado State University - Fort Collins Matthew orM an United States Department of Agriculture Follow this and additional works at: http://lib.dr.iastate.edu/eeob_ag_pubs Part of the Agronomy and Crop Sciences Commons, Behavior and Ethology Commons, and the Genetics Commons The ompc lete bibliographic information for this item can be found at http://lib.dr.iastate.edu/ eeob_ag_pubs/237. For information on how to cite this item, please visit http://lib.dr.iastate.edu/ howtocite.html. This Article is brought to you for free and open access by the Ecology, Evolution and Organismal Biology at Iowa State University Digital Repository. It has been accepted for inclusion in Ecology, Evolution and Organismal Biology Publications by an authorized administrator of Iowa State University Digital Repository. For more information, please contact [email protected]. A New Species of Cotton from Wake Atoll,Gossypium stephensii(Malvaceae) Abstract Wake Atoll is an isolated chain of three islets located in the Western Pacific. Included in its endemic flora is a representative of the genus Gossypium colloquially referred to as Wake Island cotton. Stanley G. Stephens pointed out that “Wake Island cotton does not resemble closely either the Caribbean or other Pacific forms.” Taking into consideration morphological distinctions, the geographic isolation of Wake Atoll, and newly generated molecular data presented here, we conclude that the cottons of Wake Atoll do in fact represent a new species of Gossypium, here named Gossypium stephensii. This name is chosen to commemorate the eminent natural historian, evolutionary geneticist, and cotton biologist, S. G. Stephens. Keywords Chloroplast DNA, Pacific cO ean, phylogeny, targeted sequence capture, taxonomy Disciplines Agronomy and Crop Sciences | Behavior and Ethology | Ecology and Evolutionary Biology | Genetics Comments This article is published as Gallagher, Joseph P., Corrinne E. Grover, Kristen Rex, Matthew Moran, and Jonathan F. Wendel. "A new species of cotton from Wake Atoll, Gossypium stephensii (Malvaceae)." Systematic Botany 42, no. 1 (2017): 115-123. 10.1600/036364417X694593. Posted with permission. Rights Works produced by employees of the U.S. Government as part of their official duties are not copyrighted with the U.S. The onc tent of this document is not copyrighted. This article is available at Iowa State University Digital Repository: http://lib.dr.iastate.edu/eeob_ag_pubs/237 Systematic Botany (2017), 42(1): pp. 115–123 © Copyright 2017 by the American Society of Plant Taxonomists DOI 10.1600/036364417X694593 Date of publication March 1, 2017 A New Species of Cotton from Wake Atoll, Gossypium stephensii (Malvaceae) Joseph P. Gallagher,1 Corrinne E. Grover,1 Kristen Rex,2 Matthew Moran,3 and Jonathan F. Wendel1,4 1Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, Iowa 50011, U. S. A. 2Colorado State University, Center for Environmental Management of Military Lands in support of the US Air Force, 611 Civil Engineer Squadron, Fort Collins, Colorado 80523, U. S. A. 3USDA Forest Service, Chugach National Forest, Anchorage, Alaska 99501, U. S. A. 4Author for correspondence ([email protected]) Communicating Editor: Martin Wojciechowski Abstract—Wake Atoll is an isolated chain of three islets located in the Western Pacific. Included in its endemic flora is a representative of the genus Gossypium colloquially referred to as Wake Island cotton. Stanley G. Stephens pointed out that “Wake Island cotton does not resemble closely either the Caribbean or other Pacific forms.” Taking into consideration morphological distinctions, the geographic isolation of Wake Atoll, and newly generated molecular data presented here, we conclude that the cottons of Wake Atoll do in fact represent a new species of Gossypium, here named Gossypium stephensii. This name is chosen to commemorate the eminent natural historian, evolutionary geneticist, and cotton biologist, S. G. Stephens. Keywords—Chloroplast DNA, Pacific Ocean, phylogeny, targeted sequence capture, taxonomy. Wake Atoll is an isolated chain of three islets (Peale, Wake, United States Air Force, we validated the distinguishing and Wilkes) located in the Western Pacific approximately characteristics of the Wake Atoll forms relative to G. 3,500 km west of Hawaii and 2,500 km east of Guam (Fig. 1; hirsutum (Fryxell 1992). We further assessed its distinctive- Levenson 2008). The remoteness of this island group in ness and taxonomic status through the use of extensive conjunction with its diminutive land area constrains its DNA sequence data from both the nuclear and chloroplast floristic and faunistic diversity, but also provides the genomes, which reveal a clear differentiation of the Wake opportunity for evolutionary endemism. The floristic com- Atoll cottons from a large sampling of G. hirsutum acces- munities of Wake Atoll have been cataloged by several sions. Taking into consideration morphological distinctions, naturalists, including E. H. Bryan Jr. and F. R. Fosberg (Bryan the geographic isolation of Wake Atoll, and newly generated 1942; Fosberg 1959). Within the Tournefortia L. (Boraginaceae)- molecular data presented here, we conclude that the cottons dominated forest found on the islets of the atoll, there is a of Wake Atoll do in fact represent a new species of representative of the genus Gossypium L. that has often been Gossypium, here named Gossypium stephensii J. Gallagher, identified as G. hirsutum L., a member of the allopolyploid C. Grover, & Wendel. This commemorative name honors the clade of cottons, and is colloquially referred to as Wake Island late S. G. Stephens (1911–1986), an underappreciated and cotton (Fosberg 1959; Levenson 2008). remarkably insightful natural historian, evolutionary geneti- The Wake Atoll cotton specimens collected by Bryan and cist, and cotton biologist (Wendel and Goodman 2011). Fosberg were labeled Gossypium hirsutum var. religiosum (L.) G. Watt (Bryan 1942; Fosberg 1959). As Fryxell (1968) pointed out, the name Gossypium religiosum L. is “the most Materials and Methods tortured of all the Linnean names in Gossypium” due to its — complex history. While Linnaeus originally named G. religiosum Plant Materials Seeds collected on Wake Atoll by Ray Fosberg (formerly USGS, Washington, D.C.) were obtained from Paul A. Fryxell in 1767, Watt (1907) reduced it to synonymy with G. hirsutum, (formerly University of Texas, Austin) by J. Wendel. Additional collec- after his examination of the original holotype. Fryxell (1968) tions were made by M. Moran and K. Rex. Plants were grown in the notes that the holotype itself bears the annotation “in Indiis,” R.W. Pohl Conservatory at Iowa State University from these original suggesting a specimen origin in either the West Indies or India. seed collections. For comparative studies, we also sampled widely from Thus, we conclude that this name has no bearing on the nam- the six other allopolyploid (AD genome) species of Gossypium (Grover et al. 2015), as well as from representative diploids that serve as models ing of the new entity described here. of the ancestral A- and D-genome donors (Appendix 1; see Wendel and Wake Atoll cotton was included in early biogeographic Grover 2015). DNA was extracted from leaves of each accession using research on the genus. Stephens (1966) considered Wake the Qiagen DNeasy Plant Mini Kit (Qiagen, Valencia, California), as per Island cotton in his work on oceanic dispersal, treating it as manufacturer instructions. Sequence Capture and Sequencing — Sequencing libraries were a wild form of G. hirsutum. Notably, he pointed out that “ constructed at West Virginia University Genomics Core Facility (http:// Wake Island cotton does not resemble closely either the genomics.as.wvu.edu/) using the Illumina TruSeq kit. Following library Caribbean or other Pacific forms,” noting its “sprawling construction, DNA libraries underwent targeted sequence capture with shrub” growth habit, “densely hairy” pubescence, and larger custom bait sequence using the Mycroarray MYbaits kit (http://www ’ than average petal spot in comparison to the other Pacific .mycroarray.com/), as per the manufacturer s protocol. Our custom bait sequence pool was designed to enrich 267 genes, as detailed in cottons (Stephens 1966). With consideration of prevailing Appendix 2. Target-enriched libraries were then sent to either the Iowa ocean currents in conjunction with seed buoyancy and salt- State DNA Facility (http://www.dna.iastate.edu/) or the Beijing Geno- water survival tests, Stephens suggested that Wake Island mics Institute (http://www.genomics.cn/en/index), where they were cotton may have originated following dispersal from the sequenced (150-bp paired end) on an Illumina HiSeq 2500. Sequence Assembly — Reads were quality trimmed using sickle ( Joshi western coast of Mexico (Stephens 1966). and Fass 2011) and were mapped to the G. raimondii D-genome reference In our studies of these older, as well as more recent, collec- sequence (Paterson et al. 2012) for nuclear genes, or to the G. hirsutum tions made by members and support contractors of the chloroplast genome (Lee et al. 2006) for chloroplast